Lubricant compositions



mama Feb. 10, 1948 LUBRICANT COMPOSITIONS David W. Young, Roselle. and'William ,JfSnai-ks.

Cranford. N. J., ass-ignore to Standard Oil De- 7 velopment Company, a corporation of Delaware No Drawing. Application January 15, 1944,

Serial No.518.393 I 9 Claims- (Cl. 252-56) This invention relates to the solvent separation of high molecular weight organic compounds containing carbon and hydrogen and some inorganic element such as oxygen or nitrogen, and having molecu ar weight above 2,000, and to the use of the resulting separated product for various purposes. More particularly the invention relates to the solvent precipitation of high molecular weight polyesters of a dibaslc acid and arglycol, in order to recover therefrom a product substantially completely soluble in highly paraflinic oils, especialy of the lubricating oil boiling range, even at low temperature, in other words, a polymer that does not settle out of solution at low temperatures or high temperatures in a high viscosity index mineral oil.

The original application Serial No. 504,754, filed October 2, 1943, of which the present application is a continuation-in-part, discloses the preparation of certain types of polyesters, such as made by condensing dilinoleic acid with ethylene glycol or decamethylene glycol, and the use of the resulting products in hydrocarbon compositions such as lubricating oils, gas oils, paraffln wax. asphalt, etc.

The polyesters chiefly described in that application, and preferred'for use in the present invention, are those made from 'dimeric fatt acids or esters thereof, such as made by Bradley & Johnson (Ind. Eng. Chem. 33, 86, (1941)) for the preparation of methyl dilinoleate from dehydrated castor oil. Soy been 011 is also satisfactory, and is even preferred.

The following is given as a specific example of the preparation of a suitabe dimer acid and subsequent condensation with a glycol to produce the preferred type of polyester. Soy bean oil is converted by methanolysis to methyl esters, as

by heating to 70 C. with a liberal excess of methanol in the presence of a substantial portion of sodium methalate for several hours, and then the distilled methyl esters are polymerized by heating to.300 C. with a suitable catalyst such as 0.3% of anthraquinone, fora suitable period such as about 10-30 hours. Unpolymerized esters are then removed by disti'lation under reduced pressure of' 1-5 mm. and the residual methyl dilinoleate is carefully fractionated in a short path pot still (a modified alernbic flask) at 2 to 50 microns, or in a yclic molecular still at 2 to 5 microns. The several distilled dimer methyl esters of soy bean oil, i. e., methyl dilinoleate, had an index of refraction of N SO/D 1.4766.

This dimer acid ester is then used as raw material in the following experimental work.

' about by volume of 99% isopropyl alcohol,

. present in the reaction at any time.

2 EXAMPLE 1 4 A mixture of 37 grams of the methyl dilinoleate described above and 11.2 grams of decamethylene glycolwas heated with about 0.25 gram of paratoluene sulfonic acid as catalyst, under nitrogen,

for-about 98 hours. A gentle stream of nitrogen through the reaction mass served to stir the mixture. and to facilitate removal of acohcl formed in the reaction. No air or oxygen was The resulting polyester had a molecular weight of about 22,500 by viscosity test; it was soluble in chloroform at room temperature and insoluble in Barosa 43 mineral oil (a highly paraifinic lubricating oil having a viscosity of 43 seconds Saybolt at 210 F. and a viscosity index of about or 112). However, a 6% solution of such polyester in such parafllnic oil, which gradually cooled, showed a cloud point of 15 C.

The primary object of the present invention is to subject such a polyester to solvent separation in order to obtain therefrom a fraction com pletely soluble in highly parafllnic oil even at extremely low temperatures.

Thirty grams of the polyester thus obtained was dissolved in 200 grams of Barosa 43 mineral oil at C. The mineral oil had been saturated with nitrogen at room temperature, and nitrogen was added to the all solution as the temperature was increased to 140 C. This was for the purpose of avoiding any possibility of oxidation of the olyesters during the solvent separation. The polymer-oil mixture was then placed in a l-liter flask under an atmosphere of nitrogen and then placed in an ice-box at about l5-20 F. for 17 hours, during which time some of the polyesters separated out of solution and settled to the bottom of the flask while other particles of precipitated polyesters remained suspended in the oil. The cold mixture was filtered through paper and a layer about 10 mm.

thick of Hy-F'low, which is a calcined diatomaceous earth, at about 15-20 0., using vacuum to assist in the filtration. The filtrate which was then only slightly turbid was treated with about 15% by volume of dlbutoxy ethyl phthalate and in order to precipitate the rest of the polyester which was substantially completely dissolved in the Barosa mineral oil. The dibutoxy ethyl phtha ate was merely used to solubilize the alcohol into the polymer-oil blend. The amountof soluble polyester thus recovered was about 17 grams and it had an average molecular weight or about 3 EXAMPLEZ The solvent-precipitated soluble polyester made as described above in Example 1 was tested in solution in various types of mineral oil. When dissolved in various concentrations ranging from 1 to 5% in a parafilnic lubricating 011 base stock consisting of 90% of a Pennsylvania neutral oil having a viscosity of about 141 seconds at 100 F., aviscosity index of 102, a pour point of +30 F. and a cloud point of +32 F., and of a bright stock, the following pour, cloud and viscosity data were obtained.

, TABLE I Solutions of soluble polyester in lubricating oil Sayholt Vis- A. S. T. M. cnsltytJ Sea,

W lif 100 F. 210 F.

'lestoil +30 +31 185.2 45.82 103 Test0il+l% Polyester ---20 +32 216.7 50. 17 126.5 Test 0111:215 Polyester" +32 280.6 58.84 138 Test Oil t.0fl olyester 0 +32 408.9 78.92 145 I Converted from kinematic. v

The above table shows that this soluble polyester is a potent V. I. improver since it increased the viscosity index from 103 up to 145 in 5% concentration, and also has very substantial pour-depressing properties, obtaining the lowest pour EXAMPLE3 In order to study further the cloud depressing effect, the soluble polyester was dissolved at various concentrations ranging from 0.5% to 6.3%, in a high octane number Diesel fuel base stock (having a cetane number of 59.7), which is a highly paraftlnic oil, The cloud point data obtained were as follows:

TABLE II Cloud point, C. Diesel fuel 4.2 Diesel fuel+0.5% soluble polyester 7.3 Diesel fuel+l.4% soluble polyester 5.8 Diesel fuels-3.0% soluble polyester 5.0 Diesel fuel+6.3% soluble polyester -4.2

These data indicate that the soluble polyester has a very pronounced and highly unexpected effect in lowering the cloud point of the paraffinic Diesel fuel base stock, especially in low concentration up to about 0.5% which lowered the cloud point from 4.2 'C. to -7.3 0. Although data on lower concentrations is not available at present, it is believed that even lower cloud points are obtainable with concentrations of soluble polyesters ranging from about 0.2 to 0.4%. These polyesters also raise the cetane number of gas oils used as Diesel fuel base stocks.

The Diesel fuel base stock used in the above test is known as CFR (cooperative fuel research) fuel #3.

The soluble polyester of this invention has a number of other valuable properties, such as good compatibility with other additives in lubricating oil solutions, such as dyes, and polymerized silicones OCaHl etc.. and resistance to mechanical breakdown of molecular weight by shearing. It also has some value as a detergent in lubricating oil compositions subjected to unusually severe operating conditions such as high temperature, as in the case of Diesel engine lubricants; it is also useful as a tackiness additive in lubricating greases, cylinder lubricants, wax compositions, asphaltic compositions, etc. It may be used to good advantage as a rubber compounding agent. and it may also be used for various other purposes for which the original mixed polyester was described as useful in the original application 504,754. It is also useful in solution in refined kerosene or gas oil base stocks as a gun recoil oil.

In carrying out the solvent precipitation of this invention as described above, it is possible to vary the process by using other solvent than the Barosa 43 parafiinic lubricating oil. For instance, other parafilnic lubricating oils having a V, I. of about 100 may be used or lighter parafllnic mineral oil fractions may be used, such as a paraflinic gas oil or a petroleum ether or other types of paraflinic naphtha, or even liquefied gaseous hydrocarbons such as propane, butane, etc., may be used, in which latter case the technique used may be similar to that used in the propane precipitation of asphalt from lubricating oil stocks, namel by heating the mixture to effect complete solution, and then cooling and/or reducing the pressure to precipitate out the least soluble polyester fractions which normally tend to precipitate out of the paraflinic lubricating oil solution at low temperature. If desired, even naphthenic or aromatic oils or halogenated hydrocarbons such as chloroform and the like may be used, or mixtures of various hydrocarbon oils or other solvents may be used. In case a material is used as solvent which completely dissolves the mixed polyesters even at low temperature, then a small amount of non-solvent or anti-solvent is added to the solution in order to cause precipitation of the least soluble polyester fraction. Suitable nonsolvents include the lower alcohols, such as methanol, ethanol, isopropyl alcohol, etc., or lower ketones such as acetone and the like, or ordinary water, or mixtures.

If desired, the precipitated insoluble polyester fraction may be separated from the residual solution by settling and decanting, followed, if desired, by washing with a highly parafllnic oil, e. g., naphtha, petroleum ether, or a lube oil fraction.

Although separation of the polyesters by solvent precipitation as above described i preferred, solvent extractions may also be used under some circumstances, such as by contacting the polyester with a highly paraflinic oil at low temperature, such as 015 F. in order to extract the fractions of polyester which are soluble in the paraflinic oil and to leave undissolved the fractions which are insoluble in such an oil. Solvent extraction may also be carried out at elevated temperatures such as to F, at which the polyester is liquid, using as solvent a material such as phenol, nitrobenzene, liquid S02, chloroform, chlorobenzene, alcohol mixtures, etc.

In preparing the crude or mixed polyester, vari.

29, 1947 which lists a number of glycols or (maydroxy organic compounds which may be used ranging from ethylene glycol to higher aliphatic glycols such as IZ-hydroxy stearol or higher, as

well as other compounds containing aromatic or mixed aromatic aliphatic organic groups between the two hydroxyl groups. Various saturated as well as unsaturated fatty acids may be used in preparing the dimeric fatty compounds having an organic, preferably aliphatic or mixed aliphatic aromatic hydrocarbon, group between two CO groups representing either carboxyl group or lower aliphatic, e. g., methyl, ester group.

Although it is not intended that the invention be unnecessarily limited by any theories as to the operation or the invention, it is believed that the highly unexpected advantages of the invention are partly due to the removal by solvent precipitation of polyesters containing cross-linkages which tend to cause gel formation or insolubility, and partly due to the removal of polyesters (when formulated from the dimer acid and glycol) containing terminal groups which tend to promote insolubility, such as carboxyl group, because the insoluble polyester thrown down by solvent precipitation gave an acidtitration whereas the soluble polyester gave a neutral titration. In the experimental work the low temperature Barosa 43 mineral oil soluble polymers were removed from the oil by the dibutoxy ethyl phthalate-alcohol non-solvent procedure and then, titrated at 25 C. with 0.1 N alcoholic potassium hydroxide using phenolphthalein as indicator. The solvent for the reaction was dry chloroform. This procedure has been used by Paul J. Flory (see Journal of the American- Chemical Society, vol. 62, page 1059, May 1940) to determine the end group present in other polyesters. the soluble polymer gave 0.0 ml. titration to end point with 0.1 N alcoholic potassium hydroxide,.

while grams of the oil-insoluble polymer gave a titration of 1.4 ml. of 0.1 N KOH.

Although the invention is believed particularly applicable to the'solvent separation of polyesters made by the condensation of a'glycol with a'dimeric fatty acid or ester, especially one having more than carbon atoms between the two COO groups, the invention is considered broadly applicable to the solvent separation of other types of polyesters having a molecular weight above 2,000, preferably between 6,000 and 30,000, such as polyesters made by the polymerization of fatty oils. In an even broader sense it may be applied to all types of high molecular weight organic compounds of carbon and hydrogen which also contain oxygen and/or nitrogen, including synthetic polymeric compounds such as polyacrylic esters, e. g., polylauryl alpha-methacrylate, polyvinyl esters, etc.

' It is not intended that the invention be limited to the specific examples which have been given merely for the sake of illustration, but only by the appended claims in which it is intended to claim all novelty inherent in the invention and all modifications coming within the scope and spirit of the invention.

. We claim: i

l. A composition comprising a major proportion of mineral lubricating oil and about 0.1 to 10% of a polyester condensation product selected from the group which consists of a dlcarboxylic acid and lower aliphatic ester thereof and a Results show that 5 grams ofglycol. at least one of said monomeric substances having at least. 10 carbon atoms per molecule, the said polyester being completely soluble in paraflinic oil having a viscosity index of at least 100, at temperatures as low as 30 F., and being substantially free from polyester fractions less soluble in such paraflinic oil.

2. A composition comprising a major proportion of an aliphatic hydrocarbon material and about 0.1 to 10% of a polyester condensation product of methyl dilinoleate and decamethylene glycol, said polyester having an average molecular weight of about 9,000 and being completely soluble in paraffinic oil having a viscosity index of at least 100, at temperatures as low as 15F 'and being substantially free from three dimensional polyester compounds containing crosslinkages and alsofree from compounds having carboxyl terminal groups, said polyester also having viscosity improving pour depressing and cloud depressing properties, and being substantially free from polyester fractions less soluble in such parafilnic oil.

3. A composition comprising a major proportion of mineral lubricating oil and a V. I. im-

proving amount of a polyester condensation product of the reaction of a compound selected from the class consisting of dicarboxylic acids and lower aliphatic esters of dicarboxylic acids witha glycol, at least one of said monomeric substances having at least 10 carbon atoms per molecule, the said polyester being completely soluble in parafllnic oil having a viscosity index of at least 100, at temperatures as low as 30 F., and being substantially free from polyester frac- 'tions less soluble in such parafflnic oil.

4. The composition comprising, a major proportion of an aliphatic hydrocarbon material and dissolved therein a minor but improving amount of a solvent-separated polyester fraction having an average molecular weight of at least 2,000, being completely soluble in paramnic oil at temperatures as low as 15 F. and being substantially free from three-dimensional polyester compounds containing cross-linkages and also substantially free from polyester compounds having carboxyl terminal groups, said dissolved polyester fraotion being derived from a crude polyester condensation product of a dicarboxylic acid and a glycol, at least one ofwhich monomeric substances has at least. 10 carbon atoms per molecule, which crude polyester condensation product is not completely soluble in paraffinic oil at temperatures as low as 15 F.

5. A composition according to claim 4 wherein the major proportion of aliphatic hydrocarbon material is a normally solid petroleum hydrocarbon.

6. Composition according to claim 4 in which the dissolved. polyester is a condensation product of a dimerized unsaturatedhigher fatty acid with a glycol.

7. Composition according to claim 4 also eoncrude polyester condensation product of a dimerized unsaturated higher fatty acid with a glycol. not completely soluble in such waxy min'eral lubricating oil at temperatures as low as 15 F.

9. A method of preparing lubricating compositions which comprises making a high molecular weight polyester having an average molecular weight of at least about 2,000, said polyester being a condensation product or a dicarboxylic acid and a glycol at least one of which has at least 10 carbon atoms per molecule, dissolving said crude polyester product containing soluble and insoluble fractions in a paramnic hydrocarbon liquid at an elevated solution temperature. cooling the resultant solution downto at least 15 F. to'precipitate less soluble polyester compounds, filtering the solution to remove precipitated material, and incorporating the soluble polyester fraction in a petroleum oil base stock of the kerosene to lubricating oil boiling range.

DAVID w. YOUNG. WILLIAM J. SPARKS.

' 8 nnraamcas cum.

'The following references are of record in the file of this patent:

UNI'I'EDBTATES rams Number 'Name Date 2,152,683 Elchwald --Apr. 4, 1939 2123.641 Wiezevich July l2, 1938' 2,384,595 Blair Sept. 11; 1945 2,275,007 Larsen May 1, 1945 2,310,997 Ruthrofl Feb. 16. 1943 2,239,533 Mlkeska Apr. 22, 1941 2,342,113 Blair Feb. 22, 1944 2,330,773 Zimmer Sept. 28,1943

FOREIGN PATENTS Number Country Date 428,864 Great Britain May 15, 1935 OTHER REFERENCES Industrial and Engineering Chemistry. volume- Oils 8: Resins", by 

